The brain tissue they analysed came from the left temporal cortex, a region of the brain involved in emotional and social processing, of four women and four men with epilepsy. The tissue itself was healthy, having been removed to allow doctors to access underlying damaged areas.

The men had up to 52% more synapses per brain "layer" in this region than the women. While the effect of high synaptic density in this region is unknown, the team suspects that there may be other regions where women out-synapse men.

In any case, says DeFelipe, although different synaptic densities indicates different circuitry between men and women, men shouldn't get too cocky: the density of synapses in mice is greater than in humans.

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